It is a well-known fact that
clean water is absolutely essential for healthy living. Adequate supply of fresh and clean
drinking water is a basic need for all human beings on the earth, yet it has been observed
that millions of people worldwide are deprived of this.

Freshwater resources all over
the world are threatened not only by over exploitation and poor management but also by
ecological degradation. The main source of freshwater pollution can be attributed to
discharge of untreated waste, dumping of industrial effluent, and run-off from
agricultural fields. Industrial growth, urbanization and the increasing use of synthetic
organic substances have serious and adverse impacts on freshwater bodies. It is a
generally accepted fact that the developed countries suffer from problems of chemical
discharge into the water sources mainly groundwater, while
developing countries face problems of agricultural run-off in water sources. Polluted
water like chemicals in drinking water causes problem to health and
leads to water-borne diseases which can be prevented by taking measures can be taken even at the household level.

Many areas of
groundwater and surface water are now contaminated with heavy metals, POPs (persistent
organic pollutants), and nutrients that have an adverse affect on health. Water-borne
diseases and water-caused health problems are mostly due to inadequate and incompetent
management of water resources. Safe water for all can only be assured when access,
sustainability, and equity can be guaranteed. Access can be defined as the number of
people who are guaranteed safe drinking water and sufficient quantities of it. There has
to be an effort to sustain it, and there has to be a fair and equal distribution of water
to all segments of the society. Urban areas generally have a higher coverage of safe water
than the rural areas. Even within an area there is variation: areas that can pay for the
services have access to safe water whereas areas that cannot pay for the services have to
make do with water from hand pumps and other sources.

In the urban areas water gets
contaminated in many different ways, some of the most common reasons being leaky water
pipe joints in areas where the water pipe and sewage line pass close together. Sometimes
the water gets polluted at source due to various reasons and mainly due to inflow of
sewage into the source.

Ground water can be
contaminated through various sources and some of these are mentioned below.

Pesticides. Run-off
from farms, backyards, and golf courses contain pesticides such as DDT that in turn
contaminate the water. Leechate from landfill sites is another major contaminating source.
Its effects on the ecosystems and health are endocrine and reproductive damage in
wildlife. Groundwater is susceptible to contamination, as pesticides are mobile in the
soil. It is a matter of concern as these chemicals are persistent in the soil and water.

Sewage. Untreated or
inadequately treated municipal sewage is a major source of groundwater and surface water
pollution in the developing countries. The organic material that is discharged with
municipal waste into the watercourses uses substantial oxygen for biological degradation
thereby upsetting the ecological balance of rivers and lakes. Sewage also carries
microbial pathogens that are the cause of the spread of disease.

Nutrients. Domestic
waste water, agricultural run-off, and industrial effluents contain phosphorus and
nitrogen, fertilizer run-off, manure from livestock operations, which increase the level
of nutrients in water bodies and can cause eutrophication in the lakes and rivers and
continue on to the coastal areas. The nitrates come mainly from the fertilizer that is
added to the fields. Excessive use of fertilizers cause nitrate contamination of
groundwater, with the result that nitrate levels in drinking water is far above the safety
levels recommended. Good agricultural practices can help in reducing the amount of
nitrates in the soil and thereby lower its content in the water.

Synthetic organics.
Many of the 100 000 synthetic compounds in use today are found in the aquatic environment
and accumulate in the food chain. POPs or Persistent organic pollutants, represent the
most harmful element for the ecosystem and for human health, for example, industrial
chemicals and agricultural pesticides. These chemicals can accumulate in fish and cause
serious damage to human health. Where pesticides are used on a large-scale, groundwater
gets contaminated and this leads to the chemical contamination of drinking water.

Acidification.
Acidification of surface water, mainly lakes and reservoirs, is one of the major
environmental impacts of transport over long distance of air pollutants such as sulphur
dioxide from power plants, other heavy industry such as steel plants, and motor vehicles.
This problem is more severe in the US and in parts of Europe.

Chemicals in water can be both
naturally occurring or introduced by human interference and can have serious health
effects.

Fluoride.
Fluoride in the water is essential for protection against dental caries and weakening of
the bones, but higher levels can have an adverse effect on health. In India, high fluoride
content is found naturally in the waters in Rajasthan.

Arsenic. Arsenic
occurs naturally or is possibly aggrevated by over powering aquifers and by phosphorus
from fertilizers. High concentrations of arsenic in water can have an adverse effect on
health.A few years back, high concentrations of this element was found in drinking water
in six districts in West Bengal. A majority of people in the area was found suffering from
arsenic skin lesions. It was felt that arsenic contamination in the groundwater was due to
natural causes. The government is trying to provide an alternative drinking water source
and a method through which the arsenic content from water can be removed.

Lead. Pipes,
fittings, solder, and the service connections of some household plumbing systems contain
lead that contaminates the drinking water source.

Recreational use of water.
Untreated sewage, industrial effluents, and agricultural waste are often discharged into
the water bodies such as the lakes, coastal areas and rivers endangering their use for
recreational purposes such as swimming and canoeing.

Water-borne diseases are
infectious diseases spread primarily through contaminated water. Though these diseases are
spread either directly or through flies or filth, water is the chief medium for spread of
these diseases and hence they are termed as water-borne diseases.

Most intestinal (enteric)
diseases are infectious and are transmitted through faecal waste. Pathogens  which
include virus, bacteria, protozoa, and parasitic worms  are disease-producing agents
found in the faeces of infected persons. These diseases are more prevalent in areas with
poor sanitary conditions. These pathogens travel through water sources and interfuses
directly through persons handling food and water. Since these diseases are highly
infectious, extreme care and hygiene should be maintained by people looking after an
infected patient. Hepatitis, cholera, dysentery, and typhoid are the more common
water-borne diseases that affect large populations in the tropical regions.

A large number of chemicals
that either exist naturally in the land or are added due to human activity dissolve in the
water, thereby contaminating it and leading to various diseases.

Pesticides.
The organophosphates and the carbonates present in pesticides affect and damage the
nervous system and can cause cancer. Some of the pesticides contain carcinogens that
exceed recommended levels. They contain chlorides that cause reproductive and endocrinal
damage.

Lead. Lead is
hazardous to health as it accumulates in the body and affects the central nervous system.
Children and pregnant women are most at risk.

Fluoride. Excess
fluorides can cause yellowing of the teeth and damage to the spinal cord and other
crippling diseases.

Nitrates. Drinking
water that gets contaminated with nitrates can prove fatal especially to infants that
drink formula milk as it restricts the amount of oxygen that reaches the brain causing the
blue baby syndrome. It is also linked to digestive tract cancers. It causes
algae to bloom resulting in eutrophication in surface water.

Petrochemicals.
Benzene and other petrochemicals can cause cancer even at low exposure levels.

Chlorinated solvents.
These are linked to reproduction disorders and to some cancers.

Arsenic. Arsenic
poisoning through water can cause liver and nervous system damage, vascular diseases and
also skin cancer.

Other heavy metals.
Heavy metals cause damage to the nervous system and the kidney, and other metabolic
disruptions.

Salts. It makes the
fresh water unusable for drinking and irrigation purposes.

Exposure to polluted water can
cause diarrhoea, skin irritation, respiratory problems, and other diseases, depending on
the pollutant that is in the water body. Stagnant water and other untreated water provide
a habitat for the mosquito and a host of other parasites and insects that cause a large
number of diseases especially in the tropical regions. Among these, malaria is undoubtedly
the most widely distributed and causes most damage to human health.

Water-borne epidemics and
health hazards in the aquatic environment are mainly due to improper management of water
resources. Proper management of water resources has become the need of the hour as this
would ultimately lead to a cleaner and healthier environment.

In order to prevent the spread
of water-borne infectious diseases, people should take adequate precautions. The city
water supply should be properly checked and necessary steps taken to disinfect it. Water
pipes should be regularly checked for leaks and cracks. At home, the water should be
boiled, filtered, or other methods and necessary steps taken to ensure that it is free
from infection.

Minamata: environmental contamination with methyl mercury

In Minamata, Japan, inorganic
mercury was used in the industrial production of acetaldehyde. It was discharged into the
nearby bay as waste water and was ingested by organisms in the bottom sediments. Fish and
other creatures in the sea were soon contaminated and eventually residents of this area
who consumed the fish suffered from MeHg (methyl mercury) intoxication, later known as the
Minamata disease. The disease was first detected in 1956 but the mercury emissions
continued until 1968. But even after the emission of mercury stopped, the bottom sediment
of the polluted water contained high levels of this mercury.

Various measures were taken to
deal with this disease. Environmental pollution control, which included cessation of the
mercury process; industrial effluent control, environmental restoration of the bay; and
restrictions on the intake of fish from the bay. This apart research and investigative
activities were promoted assiduously, and compensation and help was offered by the
Japanese Government to all those affected by the disease.

The Minamata disease proved a
turning point, towards progress in environment protection measures. This experience
clearly showed that health and environment considerations must be integrated into the
process of economic and industrial development from an early stage.